Delete (or better move them somewhere to have a backup) all gradle-*-1.8 files

Start Android Studio again and rebuild/refresh.

It should work. Make sure to star the above bug ticket to get informed.

Little tip:
Try the new compile setting Settings -> Compiler -> Gradle and activate the third in-process build for a speed up. Depending on your project setting you might want to select the first one as well. With that my project build time reduced to 2-4 seconds (before 20+ seconds).